THE GENUS STREPTOCOCCUS 171 



ation was observed by Kurth (1891) ; but Pasquale (1893) 

 first noted that certain strains possessed this chromogenic 

 power in a very marked degree, forming under anaerobic 

 conditions an almost blood-red growth in two or three 

 days. He found this property, too, to be correlated with 

 the virulence of the cultures when injected into rabbits, 

 the chromogenic strains being always most pathogenic. 

 It is interesting to note that in two other families of bac- 

 teria the same peculiar phenomenon of a red pigment 

 under anaerobic conditions has been recorded, {Spiril- 

 lum rubrum, v. Esmarch, and Bacillus rubellus, Okada). 

 Further comparative studies are needed before this type 

 can be recognized as a distinct species. 



